High-modulus superelastic alloy wire for medical and dental purposes

Abstract

A wire used in the medical field for guiding purposes, as well as in other fields, such as in the field of orthodontics for teeth aligning purposes. The wire, when prepared for use in such applications, exhibits an innovative blend of advantageous properties, including enhanced kink resistance over stainless steel wires and enhanced stiffness over Nitinol wires, which enhance its use as a medical guidewire or stylet, and further, as an arch wire in orthodontia applications.

Description

BACKGROUND[0001]1. Field of the Invention[0002]The present invention relates to the field of medical and dental devices, and more particularly to guidewires and stylets used in intra-vascular procedures and arch wires used in orthodontia procedures.[0003]2. Description of the Related Prior Art[0004]A major requirement for medical guidewires and other guiding members, whether they are formed of solid wire or tubular members, is that they have sufficient column strength and stiffness to be pushed through passageways in a patient, such as the patient's vascular system, with minimal kinking or binding. However, the distal section of the guidewire must also be flexible enough to avoid damaging the blood vessel or other body lumen through which it is advanced. Accordingly, efforts have been made to provide guidewires having a favorable combination of both strength and flexibility in order to make them suitable for their intended uses. However, strength for pushing and flexibility for turn...

AI Technical Summary

Benefits of technology

The invention provides a wire that can be used in the medical field for guiding purposes, as well as in orthodontics for teeth aligning purposes. The wire has a unique blend of properties that make it better than stainless steel wires and Nitinol wires, including enhanced kink resistance and stiffness. The wire has a flexible metal wire core that is at least partially formed of a high-modulus superelastic alloy. This alloy exhibits both an upper plateau and a lower plateau from a 3-point bend test that are respectively greater than a similar test of binary Nitinol alloy with the same diameter as the wire core. The high-modulus superelastic alloy comprises a trinary alloy consisting of Nickel, Titanium, and Cobalt. The wire core can be a single continuous body.

Problems solved by technology

However, strength for pushing and flexibility for turning without damaging vascular walls tend to be diametrically opposed to one another, such that an increase in one usually involves a decrease in the other, as exemplified below.

However, such steel core guidewires tend to be stiff, i.e., not easily bent, and limited in their flexibility.

Unfortunately, such Nitinol guidewires are found to be quite soft while exhibiting good shape memory.

Accordingly, they are found to have limited pushability against resistance of tortuosity (e.g., in comparison to guidewires having stainless steel cores) because they tend to straighten out or return to their original shape during their advancement.

The shape memory can make it difficult for a physician to shape the tip of the guidewire with his fingers for accessing difficult to reach portions of the patient's vascular system.

However, there are drawbacks to such wire core configurations.

First, extreme care and precision are required in joining distinct sections in forming the wire core, which lends itself to significant manufacturing time and cost.

Second, potential joint failures along the length of the core represent an ever-present risk during use of the wire.

Third, while the use of stainless steel and superelastic materials in the wire core help to exhibit both column strength and kink resistance, respectively, one or more of these properties can generally be found to be impeded when joining separate materials.

Standard binary Nitinol has generally been used as the material of choice for such arch wires because of its good flexibility properties; however, such material is generally lacking in terms of its overall strength and stiffness properties.

Images